Update.
Had a brand new Throttle Body Assembly fitted on the 3rd of Oct, Odo @ 30,400 miles. This assembly comes with factory calibrated Throttle Position and Actual Pedal Position sensors etc.
The old TB was extremely clean inside.
The fault was happening daily (sometimes two or three times a day) before the throttle body was fitted. Since fitting, the car has run absolutely fine. Since fitting new TB, after starting from cold it takes far longer for the revs at idle to die down to 'warm' idle of 600 ish rpm. I would also swear that the autobox changes up and down differently / at different speeds. Throttle response 'seems' more instant at lower speeds. Could be my imagination ?.
So, assuming this has fixed the problem, we still dont know for sure which sensor (TPS or APPS or both) was playing up (which one is Pedal Position Sensor Switch A ?) as I've effectively replaced both now.
Its reasonable to suggest that the TPS fitted when new went intermittantly awry, and the replacement TPS I had fitted last year was not fitted / calibrated correctly, hence intermittantly kicking up ever since.
Notes...
De-limiter / converter has not been looked at.
Connections / solder joints etc have not been looked at.
Weathers not so hot at the moment...heat theory not fully resolved.